Acoustic insulator and method of manufacturing same

ABSTRACT

An acoustic insulator includes a first layer having an outer surface and an inner surface and a second layer having an outer surface and an inner surface. The outer layer of the second layer is disposed adjacent to and engaging the inner surface of the first layer. The first layer and the second layer form at least one protrusion extending outwardly from the acoustic insulator.

BACKGROUND OF THE INVENTION

This invention relates in general to acoustical insulators, such as for use in vehicles. In particular, this invention relates to an improved structure for such an acoustical insulator and to a method of manufacturing same.

Acoustic insulators are used in many different applications for reducing the amount of airborne noise that is transmitted to the interior of the vehicle from one side of the panel to the other and reducing noise generated from vibration of the panel. For example, acoustical insulators are often used in a variety of vehicles, including automobiles, airplanes, trains, and the like, to minimize the amount of exterior noise that is transmitted to the interior of the vehicle. Similarly, acoustical insulation panels are often used in a variety of buildings and other static structures to minimize the amount of ambient noise that is transmitted to the interior of the building.

A variety of acoustical insulators structures are known in the art. In many instances, the acoustical insulators are formed from laminates and laminated composites. It is usually desirable that such acoustical insulators have relatively high strength and rigidity characteristics and be relatively resistant to degradation from exposure to heat and moisture. When such acoustical insulators are used in vehicle applications, it is further desirable that they be relatively inexpensive and lightweight. Thus, it would be desirable to provide an improved structure for an acoustical insulator, and a method of manufacturing same, that satisfies all of these desirable characteristics.

SUMMARY OF THE INVENTION

This invention relates to an improved structure for an acoustical insulator and to a method of manufacturing same. The acoustic insulator includes a first layer having an outer surface and an inner surface and a second layer having an outer surface and an inner surface. The outer layer of the second layer is disposed adjacent to and engaging the inner surface of the first layer. The first layer and the second layer form at least one protrusion extending outwardly from the acoustic insulator.

This invention also relates to a combined acoustic insulator and supporting component including a first layer having an outer surface and an inner surface and a second layer having an outer surface and an inner surface. The outer layer of the second layer is disposed adjacent to and engaging the inner surface of the first layer. The first layer and the second layer form at least one protrusion extending from the acoustic insulator such that the at least one protrusion engages a surface of the supporting component.

The invention further relates to a method of manufacturing an acoustic insulator including providing a fiber layer and extruding a film layer onto the fiber layer. The fiber layer and film layer are then molded to form an acoustic insulator having at least one protrusion extending outwardly therefrom.

Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art acoustic insulator and a supporting component.

FIG. 2 is an enlarged sectional elevational view of portions of the prior art acoustic insulator and the supporting component illustrated in FIG. 1.

FIG. 3 is a perspective view of an acoustic insulator and a supporting component in accordance with this invention.

FIG. 4 is an enlarged sectional elevational view of portions of the acoustic insulator and the supporting component illustrated in FIG. 3.

FIG. 5 is a schematic elevational view of an apparatus for manufacturing the acoustic insulator illustrated in FIGS. 3 and 4 in accordance with the method of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated in FIG. 1 a portion of an acoustic insulator, indicated generally at 10, that is conventional in the art. The prior art acoustic insulator 10 is shown adjacent to a supporting component 12, which may be any vehicular component, such as a dash panel, wheel well, roof, package shelf, door panel, trunk floor, engine compartment wall, and the like. As illustrated, the supporting component 12 is a passenger side dash panel, and the prior art acoustic insulator 10 is disposed adjacent to a side of the passenger side dash panel such that the prior art acoustic insulator 10 is hidden from view from the interior of the vehicle by the instrument panel. The illustrated prior art acoustic insulator 10 and the supporting component 12 have a planar contour, but can be formed having any desired non-planar contour. The illustrated prior art acoustic insulator 10 can be molded to have a contour that corresponds to the contour of the supporting component 12, as shown.

The structure of the prior art acoustic insulator 10 is illustrated in detail in FIG. 2. As shown therein, the prior art acoustic insulator 10 includes a first layer 14 having an outer surface 16 and an inner surface 18. The first layer 14 may be any needled non-woven fiber pad and may be formed of cotton, polyethylene, or any combination thereof.

The prior art acoustic insulator 10 also includes a second layer 20 having an outer surface 22 and an inner surface 24. As best shown in FIG. 2, the outer surface 22 of the second layer 20 is disposed adjacent to and engages the inner surface 18 of the first layer 14. The second layer 20 may be formed from any desired material that functions as a barrier layer that does not allow the flow of air therethrough. For example, the second layer 20 may be formed from a polymer material, such as polyethylene.

The prior art acoustic insulator 10 also includes a third layer 26 having an outer surface 28 and an inner surface 30. As best shown in FIG. 2, the outer surface 28 of the third layer 26 is disposed adjacent to and engages the inner surface 24 of the second layer 20. The inner surface 30 of the third layer 26 is disposed adjacent to and engages the outer surface of the supporting component 12. The third layer 26 is preferably a fiber pad and may be formed of cotton, polyethylene, or any combination thereof and may include resinated fiber. The third layer 26 is air permeable and supports the first layer 14 and the second layer 20 on the supporting component 12 in a spaced apart manner. Supporting the first layer 14 and the second layer 20 in a spaced apart manner is desirable because contact between the second layer 20 and the supporting component 12 may produce additional noise and vibration.

Airborne noise may be transmitted through supporting component 12 from the exterior of the vehicle due to noise radiated from the engine, exhaust and tires. Noise may also be generated by vibration of the supporting component 12 transmitted from any other portion of the vehicle (not shown). The sound waves from the noise sources may be attenuated by the first layer 14 and the second layer 20 and the third layer 26. The third layer 26 may also reduce such vibration from transferring to the first layer 14 and the second layer 20, such that the acoustic insulator 10 does not amplify such vibration.

Referring now to FIG. 3, there is illustrated a portion of an acoustic insulator, indicated generally at 40, in accordance with this invention. The acoustic insulator 40 is shown adjacent to a supporting component 42, which may be embodied as any component provided on or within a conventional structure. For example, the supporting component 42 may be a vehicular component, such as a dash panel, wheel well, roof, package shelf, door panel, trunk compartment or floor, engine compartment wall, and the like. Alternatively, instead of being positioned adjacent to the supporting component 42 as shown, the acoustic insulation panel 40 may be positioned within some or all of the supporting component 42. For example, the acoustic insulation panel 40 may be positioned within a headliner, package shelf covering, door panel lining or covering, non-load bearing trunk compartment liner, engine compartment liner, and the like. Furthermore, the supporting component 42 may be embodied as a portion of a building or other static structure. The illustrated acoustic insulator 40 and the supporting component 42 have a planar contour, but can be formed having any desired non-planar contour. The illustrated acoustic insulator 40 can be molded to have a contour that corresponds to the contour of the supporting component 42, as shown in FIG. 3 and described in detail below.

In the illustrated embodiment, the supporting component 42 is a passenger side dash panel, and the acoustic insulator 40 is disposed adjacent to the interior side of the passenger side dash panel such that the acoustic insulator 40 is hidden from view from the interior of the vehicle by the instrument panel and console. Alternatively, the supporting component 42 can be embodied as a rear wheel well, and the acoustic insulator 40 can be disposed adjacent to the interior surface of the rear wheel well such that the acoustic insulator 40 is hidden from view by trunk compartment side walls or rear quarter panel trim. However, it will be appreciated that this invention may be used in any desired environment for the purposes described below.

The structure of the acoustic insulator 40 is illustrated in detail in FIG. 4. As shown therein, the acoustic insulator 40 includes a first layer 44 having an outer surface 46 and an inner surface 48. The first layer 44 may be formed from any desired material. In the illustrated embodiment, the first layer 44 is formed from a fiber material. For example, the first layer 44 may be formed from natural and/or synthetic fibers, such as cotton, hemp, wool, silk, jute, ramie, sisal, polyester, polypropylene, nylon, glass, polyethylene, or any combination thereof. It will also be appreciated that the fiber material may include additional materials and/or binding agents, although such is not required. In a preferred embodiment, the first layer 44 is a needled non-woven fiber pad. However, it will be appreciated that the fibers of the first layer 44 may be arranged or oriented in any suitable arrangement, including randomly oriented fibers. In a further preferred embodiment, the first layer 44 is formed of a combination of polyethylene and polyethylene terephthalate fibers. In a preferred embodiment, the first layer 44 has a thickness in the range of from about three millimeters to about ten millimeters in thickness and a surface density in the range of from about three hundred to about eleven hundred grams per square meter. However, the first layer 44 may be formed having any desired thickness or density.

The acoustic insulator 40 also includes a second layer 50 having an outer surface 52 and an inner surface 54. As best shown in FIG. 4, the outer surface 52 of the second layer 50 is disposed adjacent to and engages the inner surface 48 of the first layer 44. The second layer 50 may be formed from any desired material. Preferably, the second layer 50 is formed from a material that functions as a barrier layer that does not allow the flow of air therethrough. For example, the second layer 50 may be formed from a polymer material, such as polyethylene. In a preferred embodiment, the second layer 50 has a surface density in the range of from about two hundred and fifty to about six hundred grams per square meter. However, the second layer 50 may be formed having any desired thickness or density.

The acoustic insulator 40 includes at least one protrusion 56 that extends into engagement with a surface of the supporting component 42. In the illustrated embodiment, the acoustic insulator 40 has a plurality of such protrusions 56 provided therein, and each of such protrusions 56 extends into engagement with the surface of the supporting component 42, as shown in FIG. 3. Preferably, the protrusions 56 are spaced evenly apart from one another throughout the extent of the acoustic insulator 40, although such is not required. Each of the illustrated protrusions 56 includes a contact surface 60 that is defined by that portion of the inner surface 54 of the second layer 50 that engages the vehicle panel 42. The remaining portions of the inner surface 54 of the second layer 50 are spaced apart from the vehicle panel 42. As a result, at least one recessed area 58 is defined between the inner surface 54 of the second layer 50 and the adjacent surface of the supporting component 42. Therefore, the protrusions 56 support the acoustic insulator 40 on the supporting component 42 such that the areas of the contact portions 60 that engage the surface of the supporting component 42 are relatively small in comparison to the overall area of the acoustic insulator 40 and the supporting component 42. Thus, the protrusions 56 cause most of the acoustic insulator 40 to be spaced apart from the supporting component 42, while minimizing the areas of the contact portions 60 of the acoustic insulator 40 that engage the supporting component 42. It will be appreciated that the shapes of one or more of the protrusions 56 can be varied to maximize the area of the at least one recessed area 58 and to maximize the communication between the at least one recessed area 58.

In the illustrated embodiment, each of the protrusions 56 is formed generally in the shape of an inverted bell having a relatively gently curved end portion that engages the surface of the supporting component 42. Alternatively, each of the protrusions 56 may be formed generally in the shape of an inverted cone having a relatively sharply pointed end portion that engages the surface of the supporting component 42. However, it will be appreciated that the protrusions 56 may be formed having any desired shape or combination of shapes. As illustrated, the protrusions 56 may be shaped such that the at least one recessed area 58 is a single recessed area, although such is not required.

In a manner similar to that described for the prior art, noise may be transmitted through the supporting component 42 or may be generated by vibration of supporting component 42 from any other portion of the vehicle (not shown). The sound waves from this noise may be transmitted through the at least one recessed area 58 formed by the protrusions 56 and may be attenuated through the first layer 44 and the second layer 50 within the at least one recessed area 58. As the insulator may be used in a partial or fully enclosed location within the vehicle, the sound transmitted through the insulator may be reflected from the enclosing surfaces back to insulator 40 where it may be absorbed. The at least one recessed area 58 also may reduce such vibration from transferring to the first layer 44 and the second layer 50, such that the acoustic insulation panel 40 does not amplify such vibration. It will be appreciated that it may be desirable to minimize the areas of the contact portions 60 to further reduce such vibration from transfer or amplification by the acoustic insulator 40.

If desired, the size, shape, and quantity of the protrusions 56 may be selected so as to cancel specific frequencies of noises and vibrations that are generated by the supporting component 42. For example, the supporting component 42 may be an instrument panel or dashboard, and the protrusions 56 may be shaped to have varying features in various portions of the acoustic insulator 40 such that the noises and vibrations generated by the supporting component 42 are reduced by the acoustic insulator 40 when the vehicle is operated.

Referring now to FIG. 5, there is illustrated an apparatus, indicated generally at 100, for manufacturing the acoustic insulation panel illustrated in FIGS. 3 and 4 in accordance with the method of this invention. In the illustrated apparatus 100, the fiber layer 44 is initially fed from a spool 110 onto a conveyor belt 112. The fiber layer 44 may be fed in a continuous strip as illustrated or, alternatively, may be fed in the form of a series of discrete blanks. The film layer 50 is, in the illustrated embodiment, extruded from a press 114 onto the fiber layer 44. Alternatively, the film layer 50 may be applied onto the fiber layer 44 by a knife-over-roller, a curtain, a spray, or by any other conventional means. When using these alternative applicators, it is desirable (but not required) that the polymer be applied at a rate that is sufficient to maintain a small layer of polymer on the rollers, knife, or curtain to evenly coat the fiber layer 44.

The combined fiber layer 44 and film layer 50 then pass through a cutter 116, where it is cut to a desired length. The cut fiber layer 44 and film layer 50 are then conveyed to an oven 118. The oven 118 is preferably heated to a temperature sufficient to melt the film layer 50. It will further be appreciated that the oven 118 may be heated to a temperature sufficient to cure a liquid adhesive (not shown) of the fiber layer 44 and bind it to the sizing on the fibers of the fiber layer 44, although such is not required.

The combined fiber layer 44 and film layer 50 are then conveyed to a mold 120. The mold 120 is conventional in the art and is provided with an internal configuration that is designed to re-shape the combined fiber layer 44 and film layer 50 so as to form the protrusions 56 therein. This can be accomplished by causing the mold 120 to compress the combined fiber layer 44 and film layer 50 to conform to the internal configuration of the mold 120. It will be appreciated that the combined fiber layer 44 and film layer 50 may also be molded to provide a desired contour, either planar or non-planar as described above. For example, the combined fiber layer 44 and film layer 50 may be molded to have a curved shape corresponding to a curved supporting component, such as a rear wheel well. The combined fiber layer 44 and film layer 50 may be molded to a desired contour and may be molded to include the protrusion or protrusions 56 in a single molding operation, although such is not required. The molded combined fiber layer 44 and film layer 50 may then be cut as desired, for example, to form a completed acoustic insulator 40 by final trimming operations indicated at 122 to remove excess material, cut outs for pass-throughs, clips, etc., the structure of which is also known in the art.

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

1. An acoustic insulator comprising: a first layer having an outer surface and an inner surface; and a second layer having an outer surface and an inner surface, said outer layer of said second layer disposed adjacent to and engaging said inner surface of said first layer, said first layer and said second layer having a protrusion extending outwardly from said acoustic insulator.
 2. The acoustic insulator according to claim 1, wherein said first layer and said second layer have a plurality of protrusions extending outwardly from said acoustic insulator.
 3. The acoustic insulator according to claim 2, wherein said protrusions are spaced evenly apart from one another throughout the extent of said acoustic insulator.
 4. The acoustic insulator according to claim 1, wherein said protrusion is shaped generally in the shape of an inverted bell.
 5. The acoustic insulator according to claim 1, wherein said first layer is a needled non-woven fiber pad.
 6. The acoustic insulator according to claim 1, wherein said first layer is formed from at least one of cotton, hemp, wool, silk, jute, polyester, polypropylene, nylon, glass, ceramic, and polyethylene terephthalate.
 7. The acoustic insulator according to claim 1, wherein said first layer is formed of a combination of polyethylene and polyethylene terephthalate fibers
 8. The acoustic insulator according to claim 1, wherein said second layer is generally air impermeable.
 9. A combined acoustic insulator and supporting component including: a supporting component having a surface; and an acoustic insulator including a first layer having an outer surface and an inner surface and a second layer having an outer surface and an inner surface, said outer layer of said second layer being disposed adjacent to and engaging said inner surface of said first layer, said first layer and said second layer having a protrusion extending outwardly from said acoustic insulator into engagement with said surface of said supporting component.
 10. The acoustic insulator according to claim 9, wherein said supporting component is a vehicle dash panel.
 11. The acoustic insulator according to claim 9, wherein said supporting component is a vehicle wheel well.
 12. The acoustic insulator according to claim 9, wherein said first layer and said second layer have a plurality of protrusions extending from said acoustic insulation panel into engagement with said surface of said supporting component.
 13. The acoustic insulator according to claim 12, wherein the size, shape and quantity of said plurality of protrusions is selected so as to cancel specific frequencies of noises and vibrations generated by said supporting component.
 14. The acoustic insulator according to claim 12, wherein said protrusions are spaced evenly apart from one another throughout the extent of said acoustic insulation panel.
 15. The acoustic insulator according to claim 9, wherein said protrusion is shaped generally in the shape of an inverted bell.
 16. The acoustic insulator according to claim 9, wherein said first layer is a needled non-woven fiber pad.
 17. The acoustic insulator according to claim 9, wherein said first layer is formed from at least one of cotton, hemp, wool, silk, jute, ramie, sisal, polyester, polypropylene, nylon, glass, and polyethylene terephthalate.
 18. The acoustic insulator according to claim 9, wherein said first layer is formed of a combination of polyethylene and polyethylene terephthalate fibers
 19. The acoustic insulator according to claim 9, wherein said second layer is generally air impermeable.
 20. A method of manufacturing an acoustic insulator-comprising the steps of: (a) providing a fiber layer; (b) extruding a film layer onto the fiber layer; and (c) molding the fiber layer and film layer to form an acoustic insulator having at least one protrusion extending outwardly therefrom. 